The capitals of major countries around the world are getting increasingly hotter. Since the 1990s, the number of heat wave days in these areas has risen by 25%. Analysts say this is the result of high temperatures becoming longer and more intense as global warming driven by fossil fuel use coincides with the urban heat island effect. Experts warn that urgent adaptation measures are needed to protect millions of urban residents.
On the 30th (local time) of 4th, the Guardian in the United Kingdom reported an analysis recently released by the International Institute for Environment and Development (IIED), which found that in the 43 most populous capitals, the number of days per year when temperatures remained at 35 degrees or higher increased from 1,062 days in 1994–2003 to 1,335 days in 2015–2024. This shows that urban residents are being exposed each year to longer periods of more lethal heat.
In particular, Rome in Italy and Beijing in China doubled their number of days at 35 degrees or higher, and Manila in the Philippines soared threefold. Even in London in the United Kingdom, once considered to have a relatively mild climate, the number of days at 30 degrees or higher doubled, showing an acceleration of the climate crisis. In Madrid, Spain, the number of heat wave days increased from about 25 days to 47 days now.
Experts point out that over the past 30 years, extreme heat waves have likely caused the early deaths of millions of people. Older adults and low-income groups, who are vulnerable to the urban heat island effect, are particularly at risk, and one-third of urban residents worldwide live in slums or temporary residence, concentrating the damage. Anna Walnycki, a researcher at the International Institute for Environment and Development (IIED), said, "The pace of global temperature rise is far outstripping government responses," and warned, "If we fail to adapt, millions of urban residents will face not just discomfort but threats to their lives."
In fact, this summer many parts of the world turned into a "furnace." In Japan, a record high of 41.2 degrees in Jul., more than 10,000 people were taken to hospitals. In Europe, at least 16,500 people died of heatstroke from Jun. to Aug. In Brasília, the number of days per year at 35 degrees or higher was only three in the 1990s but has recently increased to 40, and Pretoria in South Africa also rose from three days to 11. Even cities once far from heat waves are joining the "hot procession."
The problem is that fossil fuel emissions causing the climate crisis are still increasing. Under the Paris Agreement's greenhouse gas reduction targets, to limit the rise in the global average temperature to within 1.5 degrees compared with before industrialization transfer, emissions must be cut by 45% by 2030. But national responses fall far short of the target.
Because of this, the international community is also moving to respond. The Global Center on Adaptation (GCA), an international organization specializing in climate change adaptation, launched the "The Heat is On" campaign, urging practical measures such as cooling centers, expanded shaded spaces, climate-adaptive work schedules, and the establishment of early warning systems. Macky Sall, GCA chair and former president of Senegal, said, "Extreme heat is not a distant future but a reality that is threatening our people, our economy, and our future right now," and emphasized, "We must invest in practical, proven solutions to protect citizens."
However, responses by countries around the world are still deemed insufficient. In the United Kingdom, official advisers to the UK Climate Change Committee raised criticism that the government's preparedness for the impacts of the climate crisis is "inadequate, piecemeal, and disjointed." Experts said, "Responding to heat waves is not a problem that can be solved simply by running air conditioners," and pointed out, "We need improved insulation and ventilation for urban buildings, public shade, and immediate budget support."